MucositisStomatitisMouth MucosaHead and Neck NeoplasmsCombined Modality TherapyAntineoplastic Combined Chemotherapy ProtocolsRadiation InjuriesRadiation DosageRadiation, IonizingDose-Response Relationship, RadiationRadiation ToleranceRadiationRadiation ProtectionRadiation MonitoringRadiotherapyRadiation Injuries, ExperimentalRadiation OncologyCosmic RadiationRadiation-Protective AgentsRadiotherapy DosageRadiation PneumonitisFluorouracilNeoplasms, Radiation-InducedGamma RaysBackground RadiationRadiodermatitisRadiometryRadiation-Sensitizing AgentsTreatment OutcomeFibroblast Growth Factor 7MouthwashesUltraviolet RaysRadiation EffectsRadiotherapy, Intensity-ModulatedDose FractionationAntimetabolites, AntineoplasticAntineoplastic AgentsNeoplasmsXerostomiaAmifostineRadiotherapy, ConformalDrug Administration ScheduleCisplatinMethotrexateAcute Radiation SyndromeLeucovorinRadiotherapy, AdjuvantGlossitisWhole-Body IrradiationOral UlcerCarcinoma, Squamous CellLaser Therapy, Low-LevelBenzydamineRadioactive Hazard Release